Thermoluminescence dating definition
The term luminescence refers to the energy emitted as light from minerals such as quartz and feldspar after they've been exposed to an ionizing radiation of some sort.
Minerals—and, in fact, everything on our planet—are exposed to cosmic radiation: luminescence dating takes advantage of the fact that certain minerals both collect and release energy from that radiation under specific conditions.
Heating these crystals (such as when a pottery vessel is fired or when rocks are heated) empties the stored energy, after which time the mineral begins absorbing energy again.
TL dating is a matter of comparing the energy stored in a crystal to what "ought" to be there, thereby coming up with a date-of-last-heated.
Artifacts which can be dated using these methods include ceramics, burned lithics, burned bricks and soil from hearths (TL), and unburned stone surfaces that were exposed to light and then buried (OSL).
Thermoluminescence was first clearly described in a paper presented to the Royal Society (of Britain) in 1663, by Robert Boyle, who described the effect in a diamond which had been warmed to body temperature.
In the same way, more or less, OSL (optically stimulated luminescence) dating measures the last time an object was exposed to sunlight.
Luminescence dating is good for between a few hundred to (at least) several hundred thousand years, making it much more useful than carbon dating.
The energy released by stimulating the crystals is expressed in light (luminescence).Crystalline rock types and soils collect energy from the radioactive decay of cosmic uranium, thorium, and potassium-40.Electrons from these substances get trapped in the mineral's crystalline structure, and continuing exposure of the rocks to these elements over time leads to predictable increases in the number of electrons caught in the matrices.The possibility of making use of TL stored in a mineral or pottery sample was first proposed by chemist Farrington Daniels in the 1950s. The potential of using thermoluminescence to date buried soils developed on colluvial and fluvial sediments from Utah and Colorado, U. During the 1960s and 70s, the Oxford University Research Laboratory for Archaeology and History of Art led in the development of TL as a method of dating archaeological materials.
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